Method of producing shaped objects



Aug. 9, 1949. D. L. GREEN 5 METHOD OF PRODUCING SHAPED OBJECTS Filed Oct. 5, 1946 i FIG. I.

%/v@0H IN SPINNING BATH IN VEN TOR.

ATTORNEY.

Patented Aug. 9, 194

UNITED STATES PATENT OFFICE METHOD OF PRODUCING SHAPED OBJECTS Duane L. Green, Buffalo, N. Y., assignor to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware Application October 3, 194.6, Serial No. 700,857

14 Claims.

This invention relates to a new and improved process of producing shaped objects from amino cellulose. More particularly, it relates to a new and improved method of producing shaped objects of a piperidyl cellulose derivative.

U. S. Patent 2,136,299 generally discloses that amino cellulose, which is soluble in dilute acetic acid, can be coagulated in the form of films or filaments from dilute acetic acid solutions by alkali. Recently, I prepared a piperidyl cellulose derivative by replacement of the p-toluenesulfonate groups of p-toluenesulfonate of glycol cellulose with piperidine. Though this piperidyl cellulose derivative is soluble in dilute acetic acid and can be coagulated from dilute acetic acid solution with caustic alkali, I found that producing filaments by spinning a dilute acetic acid solution of such piperidyl cellulose derivative into a caustic alkali bath is a highly critical process and that to constitute a satisfactory process there must be a critical balance between the spinning solution and the caustic alkali coagulating bath.

An object of this invention is to provide a new and improved method of making shaped articles of an amino cellulose.

Another object of this invention is to provide a satisfactory method of wet-spinning filaments of a piperidyl cellulose derivative.

Other and additional objects will become apparent hereinafter.

The objects of the invention are accomplished, in general, by spinning a dilute (aqueous) acetic acid solution of a piperidyl cellulose derivative in an aqueous coagulating bath containing caustic alkali in an amount sufficient to permit the production of filaments of the piperidyl cellulose derivative having a gel swelling factor of 2.5 or less. Preferably, the coagulating bath also contains a neutral salt to increase the osmotic pressure thereof. After coagulation, the filaments can be stretched and finally collected on a suitable collection device.

The gel swelling factor of the piperidyl cellulose derivative is determined as follows: A spinning solution formed of the selected piperidyl cellulose derivative in dilute (aqueous) acetic acid is spread in a thin layer on a glass or metal plate and immersed in an aqueous caustic, sodium sulfate coagulating bath of known composition. After the film has remained in the bath for three minutes, it is stripped from the plate, blotted so as to remove all excess solution and weighed immediately. It is then Washed free of alkali and salts and dried in an oven at 105 C. for two hours, and then re-weighed. The ratio of the 2 weight of the wet film to that of the dry film is called the gel swelling factor.

It is possible for this gel swelling factor to range within wide limits, such as from about 1.5 or less to 8 or more, depending upon the composition of the spinning solution and the coagulating bath. For reasons which will become apparent, such range must also include a minimum which goes at least to, and is preferably below, 2.5. For a given spinning solution composition, a high concentration of caustic soda in the coagulating bath will result in the production of filaments having a high gel swelling factor. If the alkalinity (caustic soda) of the coagulating bath is gradually decreased (with the composition of the spinning solution and the coagulating bath otherwise remaining the same), the gel swelling factor falls to a minimum and then rises again with a further decrease in the alkalinity. The gel swelling factor at the minimum will be termed the minimum gel swelling factor. The caustic concentration at minimum gel swelling is termed the minimum gel swelling alkalinity.

In general, I have found that a spinning solu tion formed of a dilute aqeous acetic acid solution of the piperidyl cellulose derivative must be spun in an aqueous caustic coagulating bath which will permit the production of yarn having a gel swelling factor of not more than 2.5. When the system is balanced so that the gel swelling factor is above 2.5, the spinning solution cannot be spun or, if the solution can be spun, the filaments and fibers will have unsatisfactory properties and characteristics. Preferably, the system is balanced to produce yarn having a gel swelling factor of less than 2.5. Optimum results are obtained when the system will produce yarn at the minimum gel swelling factor.

The stretching of the yarn after coagulation can be carried out in air, water, or in the presence of a stretch bathconsisting of an aqueous caustic solution.

- The invention may be more readily understood by reference to the detailed description when taken in connection with the accompanying illustration, in which:

Figure 1 is a diagrammatic side elevational view, with parts shown in perspective, of one embodiment of an apparatus suitable for use in accordance with the invention; and

Figure 2 is a typical gel swelling factor curve.

Referring now to Figure 1, wherein like reference numerals designate like parts, the reference numeral l0 designates a candle filter to which the spinning solution is fed in the known manner. The spinning solution is forced through the candle filter into and through a gooseneck [2 which is provided on the lower end thereof with a spinneret l4 positioned beneath the surface of the coagulating bath in a tank 16. The filaments l8 issue from the spinneret [4 below the surface of the coagulating bath 'in the tank i6 and are passed about a positively driven feed wheel and cooperating freely rotatable guide roller 22, then about freely rotating rollers 24 and 26 positioned in a stretching bath in tank 28 and then about a second positively driven wheel 30 and cooperating freely rotatable guide roller 32. The

that the peripheral speed of the respective rollers and the linear speed of the filaments thereon are the same. Feed wheel 30 is rotated at a higher speed than feed wheel so as to impart a stretch to the filaments passing through the bath in the tank 28.

From the feed wheel 30, the yarn is fed to a suitable yarn-collection device (not shown).

Figure 2 of the drawings discloses a typical gel swelling factor curve for a spinning solution of a given composition, The spinning solution consisted of 85% water, 5% glacial acetic acid and 10% of the piperidine derivative of glycol cellulose with a degree of substitution of 0.7 to 1.0 mol of piperidine per anhydrous glucose unit, the temperature being C. and the coagulating bath containing 20% sodium sulfate. From this curve, it will be noted that when the alkalinity of the bath (in percent by weight of caustic soda) is 5%, the gel swelling factor of the yarn will be 6.8. When the alkalinity of the bath (in percent by weight of caustic soda) is reduced to 3.0%, the gel swelling factor is 5.9. When the alkalinity of the bath is further reduced to 2.5%, the gel swelling factor is 5.6. When the alkalinity, is further reduced. to 2.0%, the gel swelling factor is 2.0. When the alkalinity is further reduced to 1.5%, the gel swelling factor is. 2.2. When the alkalinity is still further reduced to. 1.0%, the gel swelling factor is 3.1

Still referring to the curve, it will be noted that the curve passes through the gel swelling factor of 2.5, and that when the sodium hydroxide content of the coagulating bath is 2.0% the minimum gel swelling factor is obtained. As shown by the curve, after the minimum gel swelling factor has been obtained, further decrease in alkalinity of the coagulating bath will cause gel swelling factor to rise again. With the spinning system used for the curve, satisfactory spinnin is obtained when the percent. of caustic alkali in the coagulating bath is such as to give a gel swelling factor not above 2.5 and. preferably below 2.5. As shown in the curve, satisfactory spinning of the solution therein tested. will be had when the coagulating bath contains. from about. 1.3% to, about 2.1% caustic inthe coagulating bath. Optimum results will. be'obtained when the coagulating bath contains 2% caustic soda, the concentration which gives the minimum gel swelling factor.

In order to determine the percent caustic alkali content of the coagulating bath to be used with a spinning solution of known composition, a gel we l n r. c rv is t ine by aryin the quantity of caustic alkaliin the coagulatingvbath and-plotting the results. For any operable systern, the curve must reach a gelswelling factor of 2.5, and preferably the minimum gel swelling factor of that system should be below 2.5. Generally, in such a system the caustic alkali concentration in the coagulating bath is selected as that required to give a gel swelling factor of 2.5 specifically, the caustic concentration which gives the minimum gel swelling factor.

It is to be understood that the gel swelling factor curve need not be precisely as shown in Figure 2. With different temperatures or different salt contents, the curve may be shifted. In some systems, symmetrical curves have been obtained.

In the preferred embodiment of the invention, the coagulating bath preferably also contains a neutral salt, such as, for example, the sulfates, carbonates and phosphates of the alkali metals, for the purpose of increasing the osmotic pressure of the solution. Usually, the neutral salt is present in an amount which will be slightly below the saturation of the solution so that there will be no crystallization of the salt. In testing any system by the gel swelling factor curve, the concentration of the neutral salt is not varied but remains constant, while the caustic alkali is increased or decreased as the case may be,

The details and manner of practicing the invention will become apparent by reference to the following specific example, it being understood that this example is merely an illustrative em-- bodiment of the invention and that the scope of the invention is not limited thereto. Throughout the example, the proportions are parts by weight.

Example A spinning solution consisting of parts water, 5 parts (glacial) acetic acid and 10 parts of the piperidine derivative of glycol cellulose prepared as' hereinafter described, with a degree of substitution of 0.7 to 1.0 mol of piperidine per anhydrous glucose 'unit, was spun through a spinneret having 60 holes (each hole being 0.0035 inch in diameter) into a spinning bath consisting of 2 parts' sodium hydroxide, 25 parts sodium sulfate and 73"parts water at a temperature of 32 C. The filaments were passed through the bath for a distance of 58 inches, without contact with guides or other devices which might impart tension, and, after withdrawal, were passed to a stretch bath consisting of 10 parts sodium hydroxide and parts water at 50 C., where they Were given a 38 inch travel. The spinning'speed was 648 inches per minute and, as the coagulated yarn passed through the stretch bath, it was stretched 45% of its length. After stretching, the yarn was collected in a suitable collection device and thereafter finished.

The yarn'p'rod'uced by this example was denier, had. an elastic modulus of 34 grams per denier, and had the. following tenacities and elongations:

Dry Wet Loop Tenacity 1. 00 0. 48 0.87 Elongation per cent 27. 4 29.6 24. 4

of the reaction period, the thick gel-like mass was dissolved in pyridine and re-precipitated by pouring into a large volume of rapidly stirred water. The piperidine derivative of glycol cellulose was collected on a filter and washed thoroughly with water. Nitrogen analysis: 4%-5%; sulfur analysis: 2%5%; degree of substitution: 0.7 to 1.1 mols piperidine per glucose unit.

The piperidine derivative of glycol cellulose (ptoluenesulfonate of glycol cellulose) is soluble in dilute acids including acetic, pyridine, methanol, chloroformethanol (90-10), toluenemethanol (50-50), etc. I

The p-toluenesulfonate of glycol cellulose employed as one of the reactants was prepared as follows:

To a solution of 20 grams glycol cellulose (containing 0.33 hydroxyethyl groups per glucose unit), 28 grams sodium hydroxide and 260 cc. of water at 0 C. was added, slowly and with rapid stirring, 80 grams p-toluenesulfonyl chloride (usually purified by an alkaline wash in benzene solution followed by distillation in vacuo) dissolved in 133 grams toluene. The addition required about three minutes. The emulsion that first formed soon thickened to a stiff tough mass. After standing about 1 hour, the material was ground, washed thoroughly with water, and finally extracted with methanol at room temperature. The product contained 10.5% to 12.5%

sulfur and 1.4 to 1.6 mols p-toluenesulfonyl groups per glucose unit.

The piperidyl cellulose derivative is a derivative of cellulose having a piperidyl group attached through the nitrogen atom to the cellulose molecule in place of one or more of the hydroxyl groups of the cellulose molecule. The piperidyl cellulose derivative may contain other substituent groups than the piperidyl as herein set forth. In particular, some of the cellulose hydroxyl groups may be substituted by alkoxy groups such as methoxy, ethoxy, hydroxyethoxy, etc. and/or by still other groups such as arylsulfonyl, p-toluenesulfonyl, naphthalenesulfonyl, benzenesulfonyl, etc. In the case where the substituent group has a reactive hydroxyl group, as in hydroxyethyl cellulose, the piperidyl group may also be attached through the nitrogen in place :of the hydroxyl group of the substituent.

The piperidyl cellulose derivative is preferably prepared by the replacement of the p-toluenesulionyl groups of p-toluenesulfonate of glycol cellulose. However, it is to be understood that the invention is not restricted thereto. In general, any sulionate of glycol cellulose can be used. Thus, in addition to p-toluenesulfonate of glycol cellulose, the benzene sulfonate of glycol cellulose, the ii-naphthalene sulfonate of glycol cellulose, etc. can be used in the preparation of the piperidyl derivative.

The degree of p-toluenesulfonate or other aryl sulfonate substitution appears to be independent of the glycol derivative used as long as the glycol substitution is great enough for the derivative to be soluble in aqueous caustic solution. In general, any glycol cellulose containing at least 0.1 hydroxy ethyl groups per glucose unit can be used for the preparation of the p-toluenesulfonate or other aryl sulfonate of glycol cellulose.

In place of the piperidine derivative of glycol cellulose, other piperidyl cellulose derivatives, such as the piperidine derivative of other lowly etherified hydroxy celluloses as well as lowly etherified celluloses such as methyl and ethyl celluloses, can be used. In general, the etherified cellulose is converted tothe aryl sulfo'nate and the aryl sulfonate groups substituted by piperidine. I

The degree of piperidyl substitution can vary from 0.7 to 1.5. or 2.0 mols per glucose unit.

Though the acetic acid in the spinning solution can vary within wide limits, it is, as shown by the example, preferred to employ a spinning solution containing.5% aceticacid. The concentration of the piperidyl cellulose derivative can vary from about 5% to about 15%. The spinning (coagulating) bath preferably also contains sodium sulfate. However, as previously mentioned, any neutral salt can be employed. In general, the concentration of the neutral salt can be from about 10% to slightly below saturation of the spinning bath. Optionally, the neutral salt can be-omitted. The temperature of the spinning bath can vary from 20 to 80 C. or above. The concentration of caustic alkali in the spinning bath can vary. However, it is to be understood that for any system to be used, the caustic alkali must be of a concentration to produce a gel swelling factor of not over 2.5, and, preferably, the concentration of caustic alkali in the spinning bath should be that which produces the minimum gel swelling factor. Usually,-the

alkali concentration willbe within the range of The invention is not restricted to the production of filaments. In general, the invention can be utilized in the production of shaped objects, such as filaments, films, bristles, etc. For example, films cast from 5% acetic acid solutions of the piperidyl cellulose derivative, such as the piperidine derivative of glycol cellulose (p-toluenesulfonate of glycol cellulose), in a coagulating bath consisting of 2 parts caustic alkali, 20 parts sodium sulfate and 78 parts water, were clear and tough. The shaped objects are tertiary amino derivatives which can be used without further modification, or can be subjected to further reaction such as cross-linkin with di -halides, such as hexamethylene bromide. The amino fibers or films have exceptionally good fiber and film properties. They have excellent dye receptivity, are water-resistant, resilient, and the like.- They can be made insoluble and infusible by heat treatments. 7

The invention provides a method of producin shaped objects having satisfactory physical properties' from piperidyl cellulose derivatives.

Since it is obvious that many changes and modifications can be made in the above-described details without departing from the nature and spirit of the invention, it is to be understood that the invention is not to be limited thereto except as set forth in the appended claims.

I claim:

1. A method of producing shaped structures which comprises extruding a solution of a piperidyl cellulose derivative into an aqueous coagulating bath containing at least 10% of an alkalimetal neutral salt and caustic alkali in an amount to produce extruded articles having a gel swelling factor of not over 2.5.

2. A method of producing shaped structures which comprises extruding a solution of a piperidyl cellulose derivative into an aqueous coagulating bath containing at least 10% of an alkalimetal neutral salt and caustic alkali in an amount to produce extruded articles having a minimum gel swelling factor of less than 2.5.

3. A method of producing shaped structures which comprises extruding a dilute acetic acid 7 solution of the piperidine derivative of lowly etherified cellulose into an aqueous coagulating bath containing at least 10% of an alkali-metal neutral salt and caustic alkali in an amount to produce extruded articles having a gel swelling factor of not over 2.5.

4. A method of producing shaped structures which comprises extruding a dilute acetic acid solution of the piperidine derivative of lowly etherified cellulose into an aqueous coagulating bath containing at least 10% of an alkali-metal neutral salt and caustic alkali in an amount to produce extruded articles having a minimum gel swelling factor of less than 2.5.

5. A method of producing shaped structures which comprises extruding a solution of the piperidine derivative of glycol cellulose into an aqueous coagulating bath containing at least 10% of an alkali-metal neutral salt and caustic alkali in an amount to produce extruded articles having a gel swelling factor of not .over 2.5.

6. A method of producing shaped structures which comprises-extruding a 5% aqueous acetic acid solution of the piperidine derivative of glycol cellulose into an aqueous coagulating bath containing at least 10% of an alkali-metal neutral salt and caustic alkali in an amount to produce extruded articles having .a gel swelling factor of I not over 2.5.

7. A method of producing shaped structures which comprises extruding a 5% aqueous acetic acid solution containing 10% f the piperidine derivative of glycol cellulose into an aqueous coagulating bath containing at least 10% of an ..a;lkali-metal neutral salt and caustic alkali in an amount to produce extruded articles having a gel swelling factor of not over 2.5.

8. A- method of producing shaped structures which comprises extruding a 5% aqueous acetic solution containing of the piperidine de- :1

rivative :of glycol cellulose into an aqueous coagulating bath containing at least 10% of an alkali-metal neutral salt and caustic alkali in an amount to produce extruded articles having a minimum gel swelling factor of less than 2.5.

9. A method of producing shaped structures which comprises extruding a 5% aqueous acetic acid solution containing 10% of the piperidine derivative of glycol cellulose into an aqueous bath containing at least 10% .of'an alkali-metal neu- =tr-alsalt'and 2 caustic alkali.

10. A method of producing shaped structures 8 which comprises extruding a 5% aqueous acetic acid solution containing 10% of the piperidine derivative of glycol cellulose into an aqueous bath containing 2% caustic alkali and sodium sulfate at a temperature of from 25 to C.

11. A method of producing shaped structures which comprises extruding a 5% aqueous acetic acid solution containing 10% of the piperidine derivative of glycol cellulose with a degree of substitution of from 0.7 to 2.0 mols of piperidine per anhydrous glucose unit into an aqueous coagulating bath containing at least 10% of an alkali-metal neutral salt and caustic alkali in an amount to produce extruded articles having a gel swellin factor of not over 2.5.

12. A method of producing shaped structures which comprises extruding a, 5% aqueous acetic acid solution containing 10% of the piperidine derivative of glycol cellulose with a degree of substitution of from 0.7 to 2.0 mols of piperidine per anhydrous glucose unit into an aqueous coagulating bath containing at least 10% of an alkali-metal neutral salt and caustic alkali in an amount to produce extruded articles having a minimum gel swelling factor of less than 2.5.

13. A method of producing shaped structures which comprises extruding a 5% aqueous acetic acid solution containing 10% of the piperidine derivative-of glycol cellulose with :a degree of substitution Of from 0.7 to 2.0 mols of piperidine per anhydrous glucose unit into an aqueous bath bath containing at least 10% of an alkali-metal neutral salt and 2% caustic alkali.

14 A method of producing shaped structures which comprises extruding a 5% aqueous acetic acid solution containing 10% of the piperidine derivative of glycol cellulose with a degree of substitution of from 0.7 to 2.0 mols of piperidine'per anhydrous glucose unit into an aqueous bath containing 2% caustic alkali and 25% sodium sulfate at a temperature of from 25 to 35 C.

DUANE L. GREEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,136,299 Haskins Nov, 8, 1938 2,186,101 Dreyfus Jan. 9, 1940 2,347,383 Cox May 2, 1944 Certificate of Correction Patent No. 2,478,265 August 9, 1949 DUANE L. GREEN It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:

Column 7, line 39, after the Word acetic insert acid; column 8, line 31, strike out bath;

and that the said Letters Patent should be read with these corrections therein that the some may conform to the record of the case in the Patent Ofiice.

Signed and sealed this 31st day of January, A. D. 1950.

THOMAS F. MURPHY,

Assistant Commissioner of Patents. 

